High resolution measurement of near-field radiative heat transfer enabled by nanomechanical resonators

Near-field radiative heat transfer (NFRHT) research currently suffers from an imbalance between numerous theoretical studies, as opposed to experimental reports that remain, in proportion, relatively scarce. Existing experimental platforms all rely on unique custom-built devices on which it is difficult to integrate new materials and structures for studying the breadth of theoretically proposed phenomena. Here, we show high-resolution NFRHT measurements using, as our sensing element, silicon nitride freestanding nanomembranes—a widely available platform routinely used in materials and cavity optomechanics research. We measure NFRHT by tracking the high mechanical quality (Q) factor ( > 2 × 10 6) resonance of a membrane placed in the near-field of a hemispherical hot object. We find that a high Q-factor enables a temperature resolution ( 1.2 × 10 − 6 K) that is unparalleled in previous NFRHT experiments. Results are in good agreement with a custom-built model combining heat transport in nanomembranes and the effect of non-uniform stress/temperature on the resonator eigenmodes.